Pyrazolone diazotype couplers



Patented Jan. 2, 1951 PYRAZOLONE DIAZOTYPE COUPLERS Sam 0. Slifkin, Binghamton, N; Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application October 10, 1947,

a Serial No. 779,217

, 4 Claims.

This invention relates to a diazotype photo-. printing material. More particularly, in one embodiment, it relates to a photoprinting material containing a, coupling component which will couple with an undecomposed diazonium compound in the density areas, after exposure to light and upon development in an alkaline medium, to produce an azo dye image. In another embodiment, it relates to a photoprinting material containing a coupling component which will couple with a decomposed diazonium component in the highlight areas upon exposure to light to give an azo dye image.

Many processes have been suggested for the production of photoprinting material, such processes differing principally in the chemical used as the light-sensitive element and in the manner of developing a dye image. The most widely knownof these processes are those which are based upon the light sensitivity of aromatic diazo compounds.

Other such processes of less importance include.

processes based upon the light sensitivity of the leuco compounds of the coal tar dyestuffs; processes based upon the oxidizin action of o-nitro groups in aromatic systems having aliphatic side chains, as for instance, o-nitrophenyl lactic acid methyl ketone; and processes based upon the light sensitivity of the o-nitro-diaminotriphenylmethane bases. With the exception of the processes'based upon the light sensitivity of aromatic diazo compounds, these suggested photoprinting processes have found no commercial adaptability either because of the instability of the compounds employed or the difliculty of developing the dye image from the undecomposed lightsensitive material. The aromatic diazo compounds have found wide commercial acceptance in two well known processes which are designated respectively as the one-component or wet-development process, and the two-component or drydevelopment process.

Inthe one-component process, the aromatic diazo compound is incorporated into a lightsensitive layer on the carrier which may be paper, foil, glass, textile material or a metallic surface. After exposure under the original to be copied, this light-sensitive layer is. developed by contact withan alkaline solution 'of'the coupling component necessary to produce the ultimately desired image.

In the two-component process, the aromatic diazo compound and the coupling component necessary to produce the dye image are both incorpor'ated in the light-sensitive layer on the carrier; In this .case, the development of the dye image is efiected after exposure by contacting the light-sensitive layer with ammonia gas. When employing a diazonium salt as the lightsensitive material, for optimum results, it is preferable to use the diazo salts derived from aromatic p-diamines and o-amino-naphthols. Other diazos have been used with varying degrees of success.

In photoprinting' processes of these types it is highly desirable to produce a copy which will have a a distinctive color, preferably a dark shade on a clear white background, so that the image will be sharp. It is also desirable to have a material which will give gradation of shade throughout the high-light and half -tone areas.

For the production of red tones, combinations of the o-diazo naphthols and such azo dye coupiers as resorcinol, phloroglucinol, and methylphenyl-pyrazolone have'been used, as disclosed in U. S. 1,444,469. These combinations reproduce the image in red tones of varying depth of shade from light red to violet. The white backgrounds of these images are readily discolored by oxidation. It has been found necessary, particularly for. the improvement. of the wash fastness properties, to add metallic salts which form lakes with the azo dyes of the'images. I

I have found that'diazotype images in deep red tones of improved density, good light iastness,

and excellent wash fastness properties can be obtained when the azo dye coupling component is a derivative of pyrazolone having the formula wherein R is an aryl radical such as phenyl, tolyl, and naphthyl' radicals.

The pyrazolone derivatives of this invention will couple with diazo compounds derived from p-diam-ines of the benzene series to form excellent dye images of deep red tone, which images have good light fastness and excellent wash fastness properties.

In a preferred embodiment, the process of this invention is carried out by coating a suitable base, such as paper, a cellulose or cellulose ester film, glass plate, textile material, gelatinized surface or metallic surface with a coating preparation containing the pyrazolone derivative, a light,- sensitive diazonium salt, a mild acid such as citric acid, thiourea and water. The coating is effected in the usual manner by applying the coating so- -ing or coating of plasticsurfaces,organicsolutions:

of high velatil ity such as alcohols, ethersand ketones, may be employed partly or wholly in the place of water.

where the base material or carrier is such that the diluent exerts no appreciable; solvent action on the carrier material. High temperature drying may thus be avoided.

In another manner of carrying outthisprocess, only the light-sensitive diazonium salt is added to the mild acid solution and coated onto the carrier. The exposure under a suitable positive is effected as above, but the image is developed by bathing the exposed element in an alkaline bath containing. the pyrazolone derivative coupling component necessary to combine with the undecomposed diazonium salt to form the red azo dye image in the unexposed areas.

:In still: another manner o-f'carryi'ng out this process; a diazonium sulfonate may be employed as the light-sens tive material. A solution of a. diazo sulfonate and a: coupling component is coated on a suitable carrier, dried-,and exposed to strong actinic light under; a suitable positive or negative. The exposed diazcniur'n' sulfonate is thereby converted" into a diazo component which. couples. w th-the coupling component to form an azo dye images Although it is not essential, it is understood that, if desired, auxiliary materials may-be added to the coating solution in any of themodifications of; this: process, whichmaterials may function as stabilizers, preservatives,.- extenders, and the like. 1 The following examples. illustrate preferred.

methods of carrying out this. invention but 'itis. understoodthat these examples. are'given by way ofillustration and not of limitat on. Unless otherwisezspecified: the partsiare by weight.

: Example I A coating solution is made-up bymixing the following ingredients into 50 cc; of water:

25' cc. alcohol f cc.'formic acid 1 gram thiourea grams citr c acid 1 gram i-phenyl-pyrazolone (5)-3-carboxylic acid 6 grams 1 monoethylamino 4 diazobenzene- ZnClz double salt This coating solution-is coated onto a sheet of cellulose acetate film by theusual method of drawing the film in a taut condition past a trough and doctor-blade into which the solution has been introduced. (Spraying methods of coating may be substituted if desired.) The coated film is then dried in the usual manner by drawing it through a heated drying chamber. Upon submitting the thus processed; sensitized film to accelerated aging tests orprolonged storage tests, it is found to have a high degree of resistance to precounling or spontaneous coupling under the condit ons of storage; Upon exposing thecoated and dried film to proper actinic light, such as light rich in ultraviolet emissions, under an original pattern and developing by drawing the exposedsensitized through an Such diluents may also be employed to make up the coating-solution in cases.

atmosphere of ammonia vapors, the image is reproduced in a deep red color which has good light fastness and excellent wash fastness properties. The background is clear and colorless and no bleeding of the image into the background can be observed.

Upon substituting 1 gram of l-naphthyl-pyrazolone C5l-3-carboxylic acid. for the 1 gram of l-phenyl-pyrazolone (5) -3-carboxylic acid in the above coating solution formula, light-sensitive coatings having similar properties and producing images of a similar red tone having good light ,tastness, and excellent wash fastness properties may bev obtained.

Erample II A coating solution is prepared by mixing the following ingredients into 100 cc. of water:

5'- grams thiourea 10 grams citric acid 1 gram. l-tolyl-pyrazolone (5)-3-carboxylic acid 3 grams l-diethylamino-3-ethoxy 4 diazoben zene-ZnClz double salt This coating solution is coated onto diazotype paper stock by the usual method of drawing the. paper in a taut condition past a trough and doc-' tor-blade into which the coating solutionhas' been introduced (spraying methods of application maybe substituted). The coated paper is then dried in the usual manner by drawing it through a heated drying chamber. Upon submitting the thus processed paper to accelerated aging tests or prolongedstorage tests, itis found to have a high degree of resistance to precoupling or spontaneous coupling under storage condi tions. Upon exposing the coated and dried paperto proper actinic lightin the same manner as in the case of Example I and developing the image by drawing the exposed sensitized paper through an atmosphere of ammonia vapors, the image is reproduced in a very rich maroon shade ofred. The image thus produced has excellent light fastness and wash fastness properties and does not bleed into the background. The background is clear and colorless and the image sharp.

Example. I I I A coating solution isprepared by mixing the, following ingredientsinto 100 cc. of water:

3 grams. citric acid 3 grams 2,5,4"-triethoxy biphenyl l diazonium.

chloride ZnClz double salt 2.5 grams v1-phenyl-pyrazolone (5') -3-carb.oxylic a grams sodiumcitrate a gramsaponin A deep red positive image is produced which has excellentlight fastness and wash fastness properties, .I la m:

-. 1. n. diazotype ph -repr du ti n.- material comprising a light-sensitive: layerqon a suitable base containing as the azo dye coupling component a compound of the formula wherein R is an aryl radical and a light-sensitive monodiazonium salt of a benzene compound having a substituted amino group in para position to the diazonium group.

3. A diazotype photo-reproduction material comprising a light-sensitive layer on a suitable base containing as the azo dye coupling component a compound of the formula C-COOH 4. A diazotype photo-reproduction material comprising a light-sensitive layer on a suitable base containing as the azo dye coupling component a compound of the formula and 1-diethylamino-3-ethoxy-4-diazo benzene ZnClz double salt.

SAM C. SLIFKIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,217,189 Sus Oct. 8, 1940 2,265,221 Zischler Dec. 9, 1941 2,334,495 Kendall et a1. Nov. 16, 1943 2,353,205 Vittum et a1. July 11, 1944 2,354,552 Schneider et al. July 25, 1944 2,455,170 Glass et a1 Nov. 30, 1948 2,459,226 Kendall et a1. Jan. 18, 1949 FOREIGN PATENTS Number Country Date 200,391 Switzerland Dec. 16, 1938 

1. A DIAZOTYPE PHOTO-REPRODUCTION MATERIAL COMPRISING A LIGHT-SENSITIVE LAYER ON A SUITABLE BASE CONTAINING AS THE AZO DYE COUPLING COMPONENT A COMPOUND OF THE FORMULA 